The invention relates to a test support of a kind that is widely used especially for the determination of components of body fluids of human beings and animals.
Whereas formerly, in the clinical laboratory, the concentrations of the components of blood, for example, have been determined almost exclusively by means of liquid reagents, in recent times so-called support-bound tests have been gaining in importance. In these the reagents are embedded in appropriate layers of a solid test carrier, onto which a drop of blood, for example, is placed. The components it contains lead to a characteristic color change in the reagents on the test carrier. This color change is immediately evaluated visually, or it is measured with the aid of an instrument, usually by reflective photometry.
Such test carriers are often in the form of test strips which consist substantially of an elongated support of plastic material with test fields provided on it. However, test carriers are also known which are in the form of square or rectangular plates. The test carriers often consist of several layers which are bonded together in various ways. The bond is often produced by glues or hot-melt adhesives. In other known test carriers a plurality of layers similar to the layers of a photographic film are applied directly one on the other. Although these methods of bonding are satisfactory for a variety of purposes, in other respects they leave much to be desired. Especially when several layers cannot be glued or bonded over their entire area, for example for reasons relating to production or design, a liquid may, under certain circumstances, fail to pass rapidly and completely enough from one layer into another.
The passage of a liquid into the individual layers is improved in such a case through a proposal disclosed in U.S. Pat. No. 3,802,842 and corresponding German Pat. No. 21 18 455, in which the actual reactive coatings lie just loosely on the support and are fixed thereon by a mesh that is stretched over them andis bonded at its margins to the support. Here again, however, the transfer of liquid from layer to layer is not entirely satisfactory.
It is therefore the object of the present invention to make available a novel bonding of the layers of diagnostic test carriers, which will avoid the above-described problems and which especially will lastingly promote the transfer of liquids from layer to layer.